This present invention relates generally to an apparatus and method for scanning and inspecting baggage. More particularly, the present invention relates to security screening systems for use at airports.
Carry-on baggage inspection systems generally utilize a scan projection (SP) image for presentation to the operator. In most baggage inspection systems, scan projection images are created by moving an object under a fan beam of x-rays from a stationary x-ray source.
In some computed tomography (CT) imaging system configurations, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as an “imaging plane”. The x-ray beam passes through an object being imaged. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated radiation beam received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam intensity at each detector location. The intensity measurements from all the detectors are acquired separately to produce a transmission profile.
In third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged such that the angle at which the x-ray beam intersects the object constantly changes. A group of x-ray attenuation measurements (e.g., projection data), from the detector array at one gantry angle is referred to as a “view”. A “scan” of the object comprises a set of views made at different gantry angles, or view angles, during one revolution of the x-ray source and detector about the object or patient being imaged.
To perform a “helical” scan, the object is continually moved via a conveyor belt while the projection data for the prescribed number of slices is acquired. The helix mapped out by the fan beam yields projection data from which images in each prescribed slice may be reconstructed. Orthographic and scan projection SP-like images can be created from helical scan data by reconstruction of the entire volume, and projecting digitally through the reconstructed volume.
During the scanning of the object, potentially harmful X-ray beams are shielded by the structure of apparatus surrounding the conveyor belt and shielding means disposed at the apparatus entry and exit points (e.g., curtains disposed on the entry and exit points). In order to provide the necessary shielding an x-ray blocking material (e.g., lead, aluminum, carbon fibers or any other material that inhibits X-rays) is disposed in the apparatus structure and the curtains disposed at the entry and exit points.
However, these curtains may obstruct the flow of baggage on the conveyor as they may cause lighter objects (e.g., smaller bags, purses, carry on luggage, etc.) to tumble or even stop on the conveyor. This is exacerbated if such a device were to be used as an initial security screening measure at airport check in as typically smaller objects, purses, coats, shoes, laptops must be placed on the conveyor for x-ray screening.
Accordingly, it is desirable to provide an apparatus and method for providing an x-ray shielding means that does not interfere with the throughput of objects through the scanning system.